This invention relates generally to the field of closures for containers of pressurized containers, typically containers for carbonated beverages, and more particularly to an improved threaded type having a tamper evident ring disposed at a lower periphery which will separate from the main body of the closure when the container is first opened. Devices of this general type are known in the art, and the invention lies in specific constructional details which permit more positive activation of the tamper evident means.
Typical prior art constructions are formed both from metallic and synthetic resinous materials, and sometimes include combinations of these materials. Threaded type closures have at least partially replaced the traditional metallic crown closure, because of improved capacity to reseal the container where only part of the contents have been consumed.
In these constructions, the tamper evident ring is located at the lower circular edge of the body of the closure, and interconnected thereto by a frangible bridge. The ring includes inwardly directed projections which are configured to slide over the threads on the container finish when the closure is installed, but which resist removal when the closure is unthreaded, this movement causing the frangible bridge to rupture and the ring to remain on the container finish as the closure is removed.
One of the principal problems encountered with this type of closure has arisen with the increased desirability of recycling the container after the contents have been consumed, irrespective of whether the container is formed of glass or synthetic resinous materials. Because of differences in materials it is usual to remove the remnants of the tamper evident ring at the recycling location. The removal of the ring is a relatively simple matter where the ring has been positively ruptured, rather than merely separated from the closure body at the time of opening of the container. In most cases, the ring will remain partially attached to the closure body, and may be manually separated prior to resealing the container. With prior art constructions, this rupture does not usually occur, because no provision has been made for the occurrence of this action. More commonly, the inherent resiliency of the material causes it to remain in unruptured condition and attached to the container finish.